Gap



NW. 6 1923. 7 9 9 0 s. T. WOODHULL ET AL GAP Filed Sept. 15, 1919 2 Sheets-Sheet 1 55 @273 W qmw .Luanszw S 2% 2 9 1 6 v 0 N GAP Filed Sept. 15, 1919 2 Sheets-Sheet 2 Patented Nov. 6, i923.

tantra SAJVZUEL T. VJOODHULL, 0F IILEDFORD. AND GEORGE J'. WALLER, OF SOMERVILLE, MASESACHUSETTS, ASSIGNORS T0 AMERICAN RADIO & RESEARCH COREORATION, OF IMEDFORD, FIASSACHUSETTS, A CORPORATION OF DELAWARE.

GAP.

Application filed September 15, 1919. Serial No. 324,015.

Tmzz whom may concern..-

Be it known that we, SAMUEL T. l t oon- HULL and GEORGE J. lVALLnn. citizens of the United States, residing at li ledford, in the county of Iili(ldl se and Connnonwealth of Massachusetts, and Somerville, in the county of Middlesex and Commonwealth of Massachusetts, respectively, have invented certain new and useful improvements in Gaps; and we do hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to spark gaps for the production of electrical oscillations of relatively high frequency and more particularly to spark gaps of the quenched type.

The advantages of series spark gaps having a relatively short gap between each pair of plates for the production of powerful and highly damped electrical oscillations are sufficiently well known so that they need not be enumerated at this time.

One object of the present invention is to provide a spark gap of the quenched type which is simple in construction and etlicient in its operation and is capable of being manufactured at a minimum cost. A further object of the invention is to provide a gap of this type which is capable of being readily assembled and disassembled in order to permit the necessary cleaning of the surfaces of the gap plates. I

With these objects in view the several features of the invention consist in certain novel features of construction, combinations and arrangements of parts hereinafter described and claimed, the advantages of which will be obvious to those skilled in the art from the following description.

In the accompanying drawings illustrating the preferred form of the invention, Figure 1 represents a front elevation of the improved gap; Fig. 2 shows an end elevation of the gap illustrated in Fig. 1; Fig. 3 is a detail illustrating a view of the back of one of the gap plates with the spacing ring attached; Fig. 4. is a detail showing a section of several of the gap plates assembled; and Fig. 5 is a transverse section upon the line 5-5 of Fig. 3, showing the manner in short gap is secured between each pair of opposed surfaces. Provision is made for enclosing each pair of sparking surfaces ina substantially air-tight chamber which is conducive to a long life of the gap plates, minimizing the corrosion and pitting of the plates due to repeated action. The apparatus as a whole is capable of being easily assembled or disassembled by an unskilled person.

The gap as a whole is supported between two upright standards 10 and 11 which are fastened to a base 12. These standards are rigidly connected together by tie rods 14 and 15 threaded at their opposite ends and connected to the standards through locking nuts 16. The gap plates are indicated at 20 and are of such a construction that they may be manufactured at a minimum cost yet when assembled in a complete gap provide an ideal form of gap chamber. The several gap plates are identical in construction' and each comprises a relatively thin sheet of electrolytic copper or similar material which is susceptible of being stamped or pressed into the desired form. As shown in Figs. 4 and 5 of the drawings each plate 20 has molded in the central portion a depressed portion 22 substantially circular in shape and having a plane face 23.

This circular depression is surrounded by an annular trough 24 pressed out of the copper plate which is of less depth than the depth of the depression for a purpose to be presently described. A pair of ears 25 are struck up from the plate outside the trough 241 and serve to connect a spacing ring 27 to the back of the plate. This ring is so shaped in cross section that it lies in the an nular trough 24 and is provided with transverse recesses 28 some of which receive the ears 25 when bent over into a retaining position. As will be observed from Figure 3 of the drawings, the spacing ring is split which enablesit to be seated properly in the groove when the several plates are clamped together. This feature is ofconsiderable importance as it prevents 'distortion of the plates due to the possibility of the ring not lyinguniformly in the groove. For convenience of description the under side of the plate as shown-in Figure '5 is designated as the front of the plate and the upper side with the spacing ring attached is designated asthe back of the plate. As shown in to'the .back of one plate will lie partially in the" trough or groove 24 formed in the next adjacent plate. The sparking surfaces of the plates are enclosed in an air-tight chamberby an insulating washer 30 of annular form which is clamped between thetwo annular projections formed by the I bottoms of the trouglisfll. As the troughs 24L are of lessdepth than the circular depressions 22, as previously described, the spark gap formed between the two surfaces 23 is somewhat less than the thickness of the washer. This insulating washer isipreferably made of what is commonly known as fish paper which is tough and substantially incompressible. If so desired this paper may be coated before embodiment in the gap with a hard wax which will tend to further aid in making the gap air-tight.

This construction produces an extreme ly eflicient gap as the spark chamber is substantially air-tight and the plates may be accurately stamped out to ensure that the sparking surfaces are the same distance apart throughout their entire areas. Afurther feature of this gap tending to promote efficiency is the effectiveness with which it is cooled. It is well known that one of the most serious difficulties militating against the use of gapsof this type is due to the difficulty in maintaining the temperature of a series gap from rising unduly high. With the present construction, owing tothe character of the plates which are made of thin sheetimetal having a relatively high coefficient of conductivity, the heat generated by the passage of the spark is rapidly dissipated. In orderto augment this dissipation of heat, circulation of air between the back of the gap plates is permitted through'the provision of the recesses 28 formed in the spacing rings 27. 'As shown heretofore each ring is provided with plurality of recesses some of which are employed to receive the connecting ears 25. These recesses permit the complete circulation of air across the backs of the plates and serve to effectually cool them.

One of the important features of the present gap is the ease with which it may be assembled and disassembled forany desired purpose; Upon reference to the drawings it will be observed that eachgap plate is )rovided with a series of openings 32 which are adapted to register with one another when the plates are assembled to permit the;

passage of assembling rods 33 therethrough. These openings in the gap plates are so located with respect to the insulating washers 3,0 that when two assembling rods are received in thelower setsof openings to hold the plates in assembled relation and 'the' washers positioned between each alternate pair of plates, the latter will rest upon the rods and be automatically centered with relaboss 46 formed upon the standard 11 and ,in

the case of the second block receives the end of a clamping screw 47 threaded in the standard 10. The clamp screw 47. is provided with a convenient form ofhan'dle -48 by which the screw may be turned to impart the requisite clamping pressure to the series of gap plates. It will be observed that the pressure applied by the clamping screw is transmitted from the end members 40 through the metal spacing rings 27 and. the interposed insulating washers 30 so that substantially all of the clamping pressure is exerted upon the washers: to maintain an air-tight sparking chamber. In order to further facilitate the assembling of the gap the several plates are preferably made rectangular or square in form and of such a size that when resting upon two insulating supports 50 they are located in a substan: tially central position with respect to the end members '40. The supporting strips 50 are preferably mounted at their opposite ones in hangers 52 formed integrally with the standards 10 and ll and may be composed of bakelite'or equivalent material. The .assembling rods are. also conveniently made of insulating material and remain in position passing through the gap plates when in operation. Theusnal terminals (not shown) may be conveniently clipped to the end plates of the gap. I

It will be obvious that this gap maybe easily assembled and disassembled and that in addition it will be impossible for an unskilled person to assemble the various portions of the gap improperly. In putting the gap together it is only necessary to assemble the plurality of gap plates upon the assembling rods and to then place'the insulating washers in position upon the rods between the respective pairs of plates. After this is accomplished the assembled plates are inserted between the upright standards resting upon the insulating strips 50 with the end members it) properly positioned in place. Upon tightening the clamping screw pressure is applied to all of the gap plates, clamping the plates and insulating washers together and providing a series of air-tight sparking chambers with the opposed surfaces of each chamber spaced the requisite distance apart.

It is of course obvious that if so desired either or all of the plates may be silver plated and certain of the plates, if so de sired, may be short circuited in the usual manner.

lVhile it is preferred to employ the specific construction and arrangement of parts shown and described, it will be understood that this construction and arrangement is not essential except so far as specified in the claims, and may be changed or modified without departing'from the broader features of the invention.

The invention having been described, what is claimed is:

1. A spark gap comprising a plurality of sheet metal plates each of substantially uniform thickness throughout and having formed therein a flat central sparking area, and an annular trough surrounding the sparking area, an insulating gasket interposed between the plates, and means for clamping the plates and gasket together to provide a substantially air-tight sparking chamber.

2. A. spark gap comprising a thin sheet metal gap plate of uniform thickness throughout and having a flat central depression therein to form a sparking area surrounded by an annular trough of less depth than the depth of the central depression.

3. A spark gap comprising a sheet metal plate having a plane sparking area formed upon the front surface, ears projecting integrally from the opposite surface of the plate, and an annular spacing member connected to the plate through the ears.

4. A spark gap comprising a series of sheet metal gap plates each of substantially uniform thickness throughout and having a central sparking surface formed therein and so located with respect to one another that the front surfaces of each alternate pair of plates are opposed, an insulating member interposed between the front surfaces of each alternate pair of plates, a metallic spacing washer connected to the back of each alternate plate, and means for clamping all of the plates and washers together in assembled relation.

5. A spark gap comprising a plurality of sheet metal plates of substantially uniform thickness throughout having depressions formed therein to provide sparking areas upon the front faces of the plates, an insulating member interposed between the front faces of two adjacent plates to separate the sparking areas and provide an air-tight sparking chamber, and means for clamping the plates and insulating member together in assembled relation.

6. A spark gap comprising a plurality of sheet metal plates each having a central depression and an annular trough formed therein and assembled with the front faces of each alternate pair of plates opposed to provide a series of sparking gaps, an insulating member received between the front faces of the plates, a metallic spacing ring received between the back faces of the plates and provided with recesses to permit the circulation of air between the back faces and the plates, and means for clamping the plates together in assembled relation.

7. A park gap comprising a series of sheet metal plates of substantially uniform thickness throughout and shaped to provide sparking areas on the opposite faces of each alternate pair of plates, spacing members of conducting and nonconducting material alternately separating the plates, and means for clamping the plates and spacing members together in assembled relation.

8. A spark gap comprising a series of thin sheet metal plates of uniform thickness each having a centrally disposed sparking area and an annular recess surrounding the area, and separating rings of conducting and non'conducting material engaging with the back and front faces of the plates respectively where the annular recess is formed.

9. A spark gap comprising a series of gap electrodes, each constructed entirely of thin sheet metal, annular spacing members separating the electrodes, end members of substantial thickness engaging with the annular spacing members at opposite ends of the electrodes, and a threaded pressure member for forcing the end members together to clamp the electrodes in assembled relation by a pressure transmitted entirely through the annular spacing members.

10. A spark gap comprising a series of relatively thin sheet metal gap plates each having a flat central depression and an annular recess surrounding the depression, a split ring seated in the annular recess, and means for securing the ring to the plate.

11. A spark gap comprising a sheet metal plate of relatively high conductivity having a central depression and an annular trough pressed therein, ears projecting integrally from the back of the plate, and a metallic ring partially lying in the trough and havingrecesses formed therein which receive the ears by Which the ring is con nected to the plate.

12. A spark gap comprising a series of sheet metal gap plates each of uniform thickness throughout and having a flat central depression and an annular recess stormed in the back face,,a spacing ring of conducting material seated in the recesses between a pair'ot opposed plates, a spacing ring of insulating material engaged between the corresponding. annular ribs formed upon the front faces of the plates to provide an air tight sparking chamber, and means for clamping the plates and spacing members together.

the recesses 13. A spark gap comprising a pair of" cess formed in the'back face, the two plates being supported back to'back, and a spacing. ring of conducting material seated in and connected to oneof the plates. I 14. A spark gap comprising a thin sheet metal plate of uniform thickness throughout 7 and having a flat central depression and an annular recess formed in one face producing a correspondingly shaped projection and annular rib upon the opposite face.

. SAMUEL r. WOODHULL.

enones aWALLEn. 

